<?php

namespace wechat;
class JSSDK
{
    private $appId;
    private $appSecret;

    public function __construct($appId, $appSecret)
    {
        $this->appId = $appId;
        $this->appSecret = $appSecret;
    }

    public function getSignPackage($url="")
    {
        $jsapiTicket = $this->getJsApiTicket();

        // 注意 URL 一定要动态获取，不能 hardcode.
        //BGG修改：201705新修改，因为是AJAX获取，所以生成签名的地址并不是当前响应地址，而是发起请求的地址，所以有可能需要通过参数传进来，PHP的话可以通过$_SERVER['HTTP_REFERER']获取
        if(empty($url)){//如果没有传入地址参数，则使用当前响应地址，来生成签名
            $protocol = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off' || $_SERVER['SERVER_PORT'] == 443) ? "https://" : "http://";
            $url = "$protocol$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";
        }


        $timestamp = time();
        $nonceStr = $this->createNonceStr();

        // 这里参数的顺序要按照 key 值 ASCII 码升序排序
        $string = "jsapi_ticket=$jsapiTicket&noncestr=$nonceStr&timestamp=$timestamp&url=$url";

        $signature = sha1($string);

        $signPackage = array(
            "appId" => $this->appId,
            "nonceStr" => $nonceStr,
            "timestamp" => $timestamp,
            "url" => $url,
            "signature" => $signature,
            "rawString" => $string
        );
        return $signPackage;
    }

    private function createNonceStr($length = 16)
    {
        $chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
        $str = "";
        for ($i = 0; $i < $length; $i++) {
            $str .= substr($chars, mt_rand(0, strlen($chars) - 1), 1);
        }
        return $str;
    }

    private function getJsApiTicket()
    {
        // jsapi_ticket 应该全局存储与更新，以下代码以写入到文件中做示例1
        $data = json_decode($this->get_php_file("jsapi_ticket.php"));
        if ($data->expire_time < time()) {
            $accessToken = $this->getAccessToken();
            // 如果是企业号用以下 URL 获取 ticket
            // $url = "https://qyapi.weixin.qq.com/cgi-bin/get_jsapi_ticket?access_token=$accessToken";
            $url = "https://api.weixin.qq.com/cgi-bin/ticket/getticket?type=jsapi&access_token=$accessToken";
            $res = json_decode($this->httpGet($url));
            $ticket = $res->ticket;
            if ($ticket) {
                $data->expire_time = time() + 1800;
                $data->jsapi_ticket = $ticket;
                $this->set_php_file("jsapi_ticket.php", "<?php exit();?>" . json_encode($data));
            }
        } else {
            $ticket = $data->jsapi_ticket;
        }

        return $ticket;
    }

    public function getAccessToken()
    {
        // access_token 应该全局存储与更新，以下代码以写入到文件中做示例
        $data = json_decode($this->get_php_file("access_token.php"));
        if ($data->expire_time < time()) {
            // 如果是企业号用以下URL获取access_token
            // $url = "https://qyapi.weixin.qq.com/cgi-bin/gettoken?corpid=$this->appId&corpsecret=$this->appSecret";
            $url = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=$this->appId&secret=$this->appSecret";
            $res = json_decode($this->httpGet($url));
            $access_token = $res->access_token;
            if ($access_token) {
                $data->expire_time = time() + 1800;
                $data->access_token = $access_token;
                $this->set_php_file("access_token.php", "<?php exit();?>" . json_encode($data));
            }
        } else {
            $access_token = $data->access_token;
        }
        return $access_token;
    }

    private function httpGet($url)
    {
        $curl = curl_init();
        curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($curl, CURLOPT_TIMEOUT, 500);
        // 为保证第三方服务器与微信服务器之间数据传输的安全性，所有微信接口采用https方式调用，必须使用下面2行代码打开ssl安全校验。
        // 如果在部署过程中代码在此处验证失败，请到 http://curl.haxx.se/ca/cacert.pem 下载新的证书判别文件。
        //BGG修改：201705新修改，此处有坑，原来的jssdk这里是设置参数为true,新版的php支持0和2，默认为2，开启SSL认证
        curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, 2);
        curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, 2);
        curl_setopt($curl, CURLOPT_URL, $url);

        $res = curl_exec($curl);
        file_put_contents("test.txt",curl_error($curl));
        curl_close($curl);

        return $res;
    }

    private function get_php_file($filename)
    {
        /*
        * BGG修改：201705新修改，增加判断了该文件不存在的情况下，自动创建一个
        * */
        $content = @file_get_contents($filename);
        if (empty($content)) {
            $content = $filename == 'access_token.php' ? '<?php exit();?>{"access_token":"","expire_time":0}' : '<?php exit();?>{"jsapi_ticket":"","expire_time":0}';
            $this->set_php_file($filename, $content);
        }
        return trim(substr($content, 15));

//    return trim(substr(file_get_contents($filename), 15));
    }

    private function set_php_file($filename, $content)
    {
        $fp = fopen($filename, "w+");
        fwrite($fp, $content);
        fclose($fp);
    }
}

